day-dream

基本解释

Those with the attention-deficit component find it difficult to concentrate, are easily distracted and likely to day-dream.
那些注意力不足的人发现很难去集中注意力，容易分心和想入非非。
Friedrich Kekule discovers the unique ring like structure of the molecule benzene right after he wakes up from a day-dream about snakes chasing their own tails and forming rings.
弗里德里希·凯库勒发现分子苯的结构想一个环状的客观事实，正是醒于当天的一个白日梦后知道的，在梦里他梦见一群蛇都在追逐着各自的尾巴，于是形成了好多环形。
It seems as if he were in a day-dream.
看起来他好像在做黄粱梦。

We have to dream beyond the day-to-day living.
梦想必须超越我们日复一日的生活。
麻省理工公开课 - 固态化学导论课程节选
So,I'm telling you from the beginning, but don't dream and think that somehow the Final's going to be so much different from your regular day-to-day performance, but to give you some reason to live after the Midterm.
所以我在开始告诉你们,但是,不要以为你们的最终成绩,和你们的平时表现,没什么关系,但这能让你们不至于期中的时候就绝望了
耶鲁公开课 - 基础物理课程节选

Read on and we'll discover how this is possible and what it could mean for the dream of all-day mobile computing.
ENGADGET
So, one day I had a wild dream about having a C-130 plane with all these materials and props inside, all ready to go!
FORBES: The Dream About An Innotribe C-130

If you daydream, you think about pleasant things for a period of time, usually about things that you would like to happen.
A daydream is a series of pleasant thoughts, usually about things that you would like to happen.